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Topic Review
Water Well
A water well is an excavation or structure created in the ground by digging, driving, boring, or drilling to access groundwater in underground aquifers. The well water is drawn by a pump, or using containers, such as buckets, that are raised mechanically or by hand. Wells were first constructed at least eight thousand years ago and historically vary in construction from a simple scoop in the sediment of a dry watercourse to the qanats of Iran, and the stepwells and sakiehs of India. Placing a lining in the well shaft helps create stability, and linings of wood or wickerwork date back at least as far as the Iron Age. Wells have traditionally been sunk by hand digging, as is the case in rural areas of the developing world. These wells are inexpensive and low-tech as they use mostly manual labour, and the structure can be lined with brick or stone as the excavation proceeds. A more modern method called caissoning uses pre-cast reinforced concrete well rings that are lowered into the hole. Driven wells can be created in unconsolidated material with a well hole structure, which consists of a hardened drive point and a screen of perforated pipe, after which a pump is installed to collect the water. Deeper wells can be excavated by hand drilling methods or machine drilling, using a bit in a borehole. Drilled wells are usually cased with a factory-made pipe composed of steel or plastic. Drilled wells can access water at much greater depths than dug wells. Two broad classes of well are shallow or unconfined wells completed within the uppermost saturated aquifer at that location, and deep or confined wells, sunk through an impermeable stratum into an aquifer beneath. A collector well can be constructed adjacent to a freshwater lake or stream with water percolating through the intervening material. The site of a well can be selected by a hydrogeologist, or groundwater surveyor. Water may be pumped or hand drawn. Impurities from the surface can easily reach shallow sources and contamination of the supply by pathogens or chemical contaminants needs to be avoided. Well water typically contains more minerals in solution than surface water and may require treatment before being potable. Soil salination can occur as the water table falls and the surrounding soil begins to dry out. Another environmental problem is the potential for methane to seep into the water.
  • 1.9K
  • 27 Oct 2022
Topic Review
PEC Reactors for Water/Wastewater Treatment
Now and in the coming years, how we use and treat water, greywater and wastewater will become more important. A suitably designed photoelectrocatalytic (PEC) reactor is one potential solution. The photoexcitation of suitable semiconducting materials in aqueous environments can lead to the production of reactive oxygen species (ROS). ROS can inactivate microorganisms and degrade a range of chemical compounds. In the case of heterogeneous photocatalysis, semiconducting materials may suffer from fast recombination of electron–hole pairs and require post-treatment to separate the photocatalyst when a suspension system is used. To reduce recombination and improve the rate of degradation, an externally applied electrical bias can be used where the semiconducting material is immobilised onto an electrically conducive support and connected to a counter electrode. These electrochemically assisted photocatalytic systems have been termed “photoelectrocatalytic” (PEC). The term is stated in the IUPAC Recommendations 2011 as “electrochemically assisted photocatalysis. The role of the photocatalyst is played by a photoelectrode, often a semiconductor”. A short description of photocatalysis is included as it can be beneficial for those unfamiliar with the topic, before moving onto PEC. This entry is adapted from https://doi.org/10.3390/w13091198
  • 1.8K
  • 20 Oct 2021
Topic Review
Urban Wetlands
Wetlands are a critical part of natural environments that offer a wide range of ecosystem services. In urban areas, wetlands contribute to the livability of cities through improving the water quality, carbon sequestration, providing habitats for wildlife species, reducing the effects of urban heat islands, and creating recreation opportunities. 
  • 1.8K
  • 13 Jan 2022
Topic Review
Addressing, Assessing and Improving Water Security
Water security is about managing too much, too little and/or too polluted water. Water security is about the increasing importance of sustainable management of water resources, drinking water and human well-being and protection of life and property from water-related disasters. Water security is about the health of ecosystems and economic development.  A groundwork of this broad and multi-faceted concept is presented to facilitate understanding, measuring and improving water security. 
  • 1.7K
  • 25 Jan 2022
Topic Review
On-Site Carwash Wastewater Treatment
The main pollutants in car wash wastewater are detergents, dirt, oil, and grease. Untreated wastewater released into rainwater sewer systems or other water bodies may pollute the water and generate excessive bubble foams, which negatively affects urban appearance. Car washes are divided into mechanical car washes and manual or self-service car washes. In general, car washes have a small operation and scale, occupy limited land, and cannot afford wastewater treatment costs. Therefore, most car washes are not equipped with wastewater treatment facilities. Consequently, the discharge of wastewater from car washes negatively affects the water quality in the surrounding environment and results in wasteful use of water resources. 
  • 1.7K
  • 22 Jun 2022
Topic Review
Microplastic Removal and Degradation Techniques
Plastics are a kind of synthetic or semisynthetic polymer that are made up of long chains of carbon atoms, and they may also have oxygen, nitrogen, or sulfur atoms attached to them. The majority of plastics are produced by factories that use fossil fuels. Microplastics are small particles of fragments and microfibers of plastic that have a diameter of less than 5 mm. Because of the widespread usage of microbeads in a variety of goods as well as the fragmentation of plastics with increasing age, the quantity of microplastic released in the aquatic environment is alarming, and so effluent water needs to be treated in wastewater plants to remove the microplastics. Different biotic and abiotic approaches have been studied in different research over the years.
  • 1.7K
  • 23 Dec 2022
Topic Review
Humidification and Dehumidification Desalination
Humidification–dehumidification desalination (HDH) is described as a novel volume reduction method that employs a carrier gas for the thermal desalination of water. Currently used for small scale desalination, the advantages provided by the HDH method are too great to be ignored. The benefits of the process include the use of low-grade energy and simple design and construction.
  • 1.7K
  • 14 Jan 2022
Topic Review
Integrated Watershed Management
Human activities mostly impact the trend and direction of rainwater, groundwater, and other river basin resources in the watershed in Africa. These activities alter river flows and the quality of usable water supplies at both highlands and lowlands. A watershed is indeed a conserved area of land that collects rain, sleet and snow, and empties or penetrates groundwater sources.
  • 1.6K
  • 26 Jan 2022
Topic Review
Mangalore
Mangalore (/mæŋɡəˈlɔːr/), officially known as Mangaluru, is a major port city of the Indian state of Karnataka. It is located between the Arabian Sea and the Western Ghats about 352 km (219 mi) west of Bangalore, the state capital, 20 km north of Karnataka–Kerala border, 297 km south of Goa. Mangalore is the state's only city to have all four modes of transport—air, road, rail and sea. The population of the urban agglomeration was 619,664 (As of 2011) national census of India. It is known for being one of the locations of the Indian strategic petroleum reserves. The city developed as a port in the Arabian Sea during ancient times; it has since developed into a major port of India that handles 75 per cent of India's coffee and cashew exports, and is the country's seventh largest container port. Mangalore has been ruled by several major powers, including the Kadambas, Alupas, Vijayanagar Empire, Keladi Nayaks and the Portuguese. The city was a source of contention between the British and the Kingdom of Mysore rulers Hyder Ali and Tipu Sultan, and was eventually annexed by the British in 1799. Mangalore remained part of the Madras Presidency until India's independence in 1947 and was unified with Mysore State (now called Karnataka) in 1956. Mangalore is also the administrative headquarters of the Dakshina Kannada district, and is a commercial, industrial, educational, healthcare and startup hub. This city's International Airport is the second-largest and second-busiest airport in Karnataka. Mangalore City Corporation is responsible for the civic administration, which manages the 60 wards of the city. The city's landscape is characterised by rolling hills, coconut palms, rivers and hard laterite soil. India's first 3D planetarium with 8K resolution display is situated in this city. Mangalore is also included in the Smart Cities Mission list and is among the 100 smart cities to be developed in India. The city has an average elevation of 22 m (72 ft) above mean sea level. Mangalore has a tropical monsoon climate and is under the influence of the southwest monsoon. (As of 2017), Mangalore was ranked the 48th best city to live in the world by a US survey, and the only Indian city in the top 50.
  • 1.6K
  • 17 Oct 2022
Topic Review
Membrane Fouling
Membrane-based separation has gained increased popularity over the past few decades, particularly reverse osmosis (RO). A major impediment to the improved performance of membrane separation processes, in general, is membrane fouling. Fouling has detrimental effects on the membrane’s performance and integrity, as the deposition and accumulation of foulants on its surface and/or within its pores leads to a decline in the permeate flux, deterioration of selectivity, and permeability, as well as a significantly reduced lifespan. Several factors influence the fouling-propensity of a membrane, such as surface morphology, roughness, hydrophobicity, and material of fabrication. Generally, fouling can be categorized into particulate, organic, inorganic, and biofouling. Efficient prediction techniques and diagnostics are integral for strategizing control, management, and mitigation interventions to minimize the damage of fouling occurrences in the membranes. To improve the antifouling characteristics of RO membranes, surface enhancements by different chemical and physical means have been extensively sought after. Moreover, research efforts have been directed towards synthesizing membranes using novel materials that would improve their antifouling performance. 
  • 1.6K
  • 18 May 2021
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